hmm... what about larch/python? python borrows a lot
from modula-3, and larch/modula-3 is supported. But of the
languages supportes as BSLs, smalltalk's type system is
probably most like python's. cf
larch/smalltalk

We proposed a new approach for the construction of
grammars and parsers for existing languages. The
approach is both very powerful and simple. We
provided a structured process and explained our
methods in detail so that others can apply our ideas
for their own grammar construction activities. We
illustrated the proposed approach with a nontrivial
case study. Using our process, we constructed in a
few weeks a complete and correct VS COBOL II grammar
specification for IBM mainframes. We not only
constructed a parser for it, but also published a
web-enabled grammar specification so that others can
use this result to conveniently construct their own
grammar-based tools for VS COBOL II, or
derivatives.